Background: Infections can trigger worsening of atopic dermatitis (AD). Objectives: To examine whether hospital-managed paediatric AD is associated with increased risk of extracutaneous infections requiring hospitalization in childhood. Methods: A nationwide-based cohort study using Danish registries was done. Children aged < 18 years with a hospital diagnosis of AD and children without a hospital diagnosis of AD were sex- and age-matched at date of AD diagnosis. Study outcomes were extracutaneous infections that led to hospitalization. AD severity was defined according to prescriptions for treatments. Results: Of 19 415 children with AD [median follow-up 7·4 years; interquartile range (IQR) 3·3–13.3] and 194 150 without AD (median follow-up 7·7 years; IQR 3·6–13·5), 56% were boys and 50% were aged < 2 years. Children with AD had an increased rate of lower respiratory [LRTI; adjusted hazard ratio (aHR) 1·79, 95% confidence interval (CI) 1·65–1·94)], upper respiratory (URTI; aHR 1·59, 95% CI 1·34–1·88), urinary tract (UTI; aHR 1·34, 95% CI 1·16–1·54), musculoskeletal (MSSI; aHR 1·33, 95% CI 1·06–1·66) and gastrointestinal infections (GITIs; aHR 1·24, 95% CI 1·14–1·35) vs. children without AD. Associations did not clearly vary with AD severity. Absolute risk difference per 10 000 person-years was 26·4 (95% CI 23·0–29·8) for LRTIs, 3·1 (95% CI 1·6–4·7) for URTIs, 3·6 (95% CI 1·8–5·4) for UTIs, 0·9 (95% CI 0·2–2·0) for MSSIs and 8·7 (95% CI 5·7–11·7) for GITIs. Conclusions: Children with hospital-managed AD have an increased risk of systemic infections that lead to hospitalization; absolute risk is generally low.